It is well known for lubricating oils to contain a number of surface active additives (including antiwear agents, dispersants, or detergents) used to protect internal combustion engines from corrosion, wear, soot deposits and acid build up. Often, such surface active additives can have harmful effects on engine component wear (in both iron and aluminum based components), bearing corrosion and/or fuel economy. A common antiwear additive for engine lubricating oils is zinc dialkyldithiophosphate (ZDDP). It is believed that ZDDP antiwear additives protect the engine by forming a protective film on metal surfaces. ZDDP may also have a detrimental impact on fuel economy and efficiency and copper corrosion. Consequently, engine lubricants may also contain a friction modifier to obviate the detrimental impact of ZDDP on fuel economy and corrosion inhibitors to obviate the detrimental impact of ZDDP on copper corrosion. Friction modifiers and other additives may also increase lead corrosion.
Further, engine lubricants containing phosphorus and sulfur compounds such as ZDDP have been shown to contribute in part to particulate emissions and emissions of other pollutants. In addition, sulfur and phosphorus tend to poison the catalysts used in catalytic converters, resulting in a reduction in performance of said catalysts.
There has been a commercial trend for reduction in emissions (typically reduction of NOx formation, SOx formation) and a reduction in sulfated ash in engine oil lubricants. Consequently, the amounts of phosphorus-containing antiwear agents such as ZDDP, overbased detergents such as calcium or magnesium sulfonates and phenates have been reduced. As a consequence, there is increasing interest in ashless additives that provide friction, antiwear, or antioxidant performance at least as good as, or even better than, the non-ashless additives discussed above. It is known that surface active ashless compounds such as ashless friction modifiers may in some instances increase corrosion of metal, namely, copper or lead. Copper and lead corrosion may be from bearings and other metal engine components derived from alloys using copper or lead. Consequently, there may be a need to reduce the amount of corrosion caused by ashless additives.
U.S. Pat. No. 3,250,710 discloses a process for preparing overbased polyvalent metal sulfonates. Among a list of suitable lists of dispersing aids, 3-hydroxy-2-butanone is disclosed.
United States Patent Application 2011/0143980 discloses oil-soluble titanium complexes derived from various α-, β-, and γ-hydroxy-carbonyl compounds (or anions thereof), including α-hydroxy-ketones. However there is no teaching of the disclosed carbonyl compounds as additives themselves, but only as precursors to additives.
A variety of patent publications such as CA 1 183 125, U.S. Pat. No. 5,387,351, U.S. 2005/0198894, U.S. Pat. Nos. 4,640,787, 4,692,257, 4,478,604, 4,237,022, GB 2 105 743, U.S. Pat. Nos. 2,443,578, 2,365,291, 5,338,470, WO 2005/087904, WO 2008/147700, WO 2008/147704, and WO 2008/144701 disclose different lubricating compositions containing hydroxycarboxylic acid amides, imides and esters as ashless antiwear agents and/or friction modifiers. None of these references disclose hydroxy-substituted ketones.
International publications WO 2010/096167, WO 2010/096168, and WO 2010/096169 disclose method of reducing wear or friction, and deposit formation and oxidation respectively. The compositions disclosed in the three international publications include lubricating compositions containing a base oil, and at least one additive selected from an anti-oxidant, a dispersant, a detergent or an anti-wear agent. None of these references disclose α-hydroxy-ketones.